CNKI: HowNet is an authoritative academic misconduct detection system in China, and its database covers a large number of academic journals and dissertations, so its detection results are widely recognized. HowNet's duplicate checking algorithm is strict, which can accurately detect the similarity of texts, but at the same time, it will misjudge some dissimilar contents as similarities, especially when faced with some professional terms or expressions in a specific context.
Free papers: The database of free papers is relatively small, mainly covering academic journals and some network resources. Its duplicate checking algorithm is loose, which may produce some errors. The price of PaperPass is relatively low, which is suitable for first draft inspection or economic scheme.
Wanfang Detection: Wanfang Detection is a duplicate checking software developed by Wan Fang Data Company, and its database covers academic journals, dissertations, conference papers and other resources. Wanfang detection adopts content-based algorithm, which can detect plagiarism and citation in the text.
Generally speaking, if users need to accurately detect the duplication of papers, it is recommended to use HowNet to check the duplication. If you need to check the first draft or an economical scheme, you can consider using Paperfree to check the copy of the first draft, and then using HowNet to check the copy of the final draft. This can better ensure the academic integrity and quality of the paper.